Many companies and other organizations operate computer networks that interconnect numerous computing systems to support their operations, such as with the computing systems being co-located (e.g., as part of a local network) or instead located in multiple distinct geographical locations (e.g., connected via one or more private or public intermediate networks). For example, data centers housing significant numbers of interconnected computing systems have become commonplace, such as private data centers that are operated by and on behalf of a single organization, and public data centers that are operated by entities as businesses to provide computing resources to customers. Some public data center operators provide network access, power, and secure installation facilities for hardware owned by various customers, while other public data center operators provide “full service” facilities that also include hardware resources made available for use by their customers. However, as the scale and scope of typical data centers has increased, the tasks of provisioning, administering, and managing the physical computing resources have become increasingly complicated.
The advent of virtualization technologies for commodity hardware has provided benefits with respect to managing large-scale computing resources for many customers with diverse needs, allowing various computing resources to be efficiently and securely shared by multiple customers. For example, virtualization technologies may allow a single physical computing machine to be shared among multiple users by providing each user with one or more virtual machines hosted by the single physical computing machine, with each such virtual machine being a software simulation acting as a distinct logical computing system that provides users with the illusion that they are the sole operators and administrators of a given hardware computing resource, while also providing application isolation and security among the various virtual machines. Furthermore, some virtualization technologies are capable of providing virtual resources that span two or more physical resources, such as a single virtual machine with multiple virtual processors that spans multiple distinct physical computing systems.
As another example, virtualization technologies may allow data storage hardware maintained at a remote, network-accessible storage service to be shared among multiple users. Each user or client may be provided with a virtualized data store which may be distributed across multiple data storage devices, with each such virtualized data store acting as a distinct logical data store that provides clients with the illusion that they are the sole operators and administrators of the data storage resources. Using such storage virtualization techniques, it may be possible for some clients to reduce the capital and management expenses associated with maintaining large amounts of data storage on client premises. Storing or replicating client data at remote storage services may also provide other benefits such as simplified backup and/or easier disaster recovery. In some scenarios, the programmatic interfaces used for reading and writing data at the remote storage service may differ from the interfaces supported for client I/Os—for example, data at the remote storage service may be organized in larger units than typical client I/O operations, or the storage protocol used at the remote storage service may differ from some of the protocols supported for client I/O. Accordingly, in such scenarios, client-initiated write operations may need to be coalesced or translated, e.g., at an intermediate device that receives the written data from the client on a data path to the storage service, before the written data is persisted at the storage service. Such data path operations may under some circumstances result in difficult-to-detect data corruption.
While embodiments are described herein by way of example for several embodiments and illustrative drawings, those skilled in the art will recognize that embodiments are not limited to the embodiments or drawings described. It should be understood, that the drawings and detailed description thereto are not intended to limit embodiments to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope as defined by the appended claims. The headings used herein are for organizational purposes only and are not meant to be used to limit the scope of the description or the claims. As used throughout this application, the word “may” is used in a permissive sense (i.e., meaning having the potential to), rather than the mandatory sense (i.e., meaning must). Similarly, the words “include,” “including,” and “includes” mean including, but not limited to.